The basic defect in cystic fibrosis (CF) has not been elucidated. There is no test available for prenatal diagnosis or carrier detection even though 1 of 1600 caucasians are born with CF and 1 of 20 are carriers. Recent advances in recombinant DNA technology may be useful in providing detection techniques, however a specific therapy will depend on identificaton of the preicse molecular defect. An altered glycosylation of glycoproteins has been a consistent finding in CF, thus studies of CF glycoproteins provide a logical approach to define the abnormal gene product. The oligosaccharide structures of selected glycopeptides from the peripheral membrane glycoproteins of CF and control fibroblasts will be determined. These CF glycoproteins were among those shown prevously to have altered fucosylation. The membrane glycoproteins will be metabiolically labeled with L-3H fucose, removed with trypsin, and after further purification on lentil-Sepharose, will be digested with Pronase. The major fucosylated glycopeptides will be selected by lectin affinity chromotography, gel filtraton and HPLC. The structures of the oligosaccharide residues will be determined by lectin binding, enzyme degradation and methylation analysis and verified by 500-MHz1H-NMR. It is anticipated that structural information will be used in future studies to select rationally the gene products responsible for the post-translational changes by examining specific glycosyltransferases using synthetic and endogenous substrates including glycopeptides herein defined. The proposed studies will define the role of altered glycosylation in the pathogenesis of CF and will provide new information on the structures of membrane glycoproteins in human cells.